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< prev - next > Crop processing Nut Processing and Oil Extraction KnO 100293_Shea nut processing (Printable PDF)
The shea tree (Butyrospermum parkii or Vitellaria Paradoxa) - commonly known as karité in
the Wolof and French languages, grows wild in the equatorial belt of central Africa between
Gambia and Sudan and also in Uganda.
The oil extracted has a relatively high melting point and is used in rural areas in the making
of foods, soap manufacture and cosmetics. Shea is mainly exported as kernels and can be
used as an extender in chocolate as its properties are similar to cocoa butter.
Most small-scale processing to extract the oil is carried out by women and provides an
important source of income.
Shea trees are not cultivated but grow as wild plants. A shea-tree will bear fruit at between 8
and 15 years but reaches full capacity for several decades after this. A tree can yield of 15 to
20 kg of fresh fruit that will produce 3 to 4 kg of dry kernels. The kernels contain 42 to 48%
oil (butter).
Women and children collect the fallen fruit and take them back to their villages for processing
into shea butter, an edible fat.
The green pulp exterior is removed. One method is to bury the fruit in the ground so that the
pulp ferments and falls off. This takes 12 days or more. The nuts are parboiled or sun dried
and then dried by smoking over an open fire for 3 to 4 days. The dried nuts can then be
stored for long periods without significant losses. Decortication is done by crushing the outer
shell to remove kernels. Shea nuts are mainly exported as smoked kernels. The kernels will
be further dried before any additional processing is carried out.
Shea nut butter
Traditionally wet processing by hand is a slow and laborious process that uses large quantities
of wood as fuel for roasting. Nuts are shelled by hand by being pounded individually using
the end of a pestle. The resulting kernel particles are aggregated and roasted on a metal
sheet over a fire. The kernels are then pounded in a mortar to produce a coarse paste and
then ground between two stones to produce a smooth paste. A small amount of water is
added to the paste and the mixture agitated by hand using a "paddling" motion. The quantity
of water added is not measured but judged by experience. The mixture is continuously stirred
for anything up to 4 hours. The length of time depends on the quality of the nuts. At the end
of this time the mixture becomes lighter in colour and more water is then added. The white
shea butter then floats to the top of the mixture. At this point the stirring action is carried
out much less vigorously. The resulting oil is decanted off the dark brown residue using a
spoon and is washed repeatedly with warm water until clean. The remaining water is removed
by heating. Impurities settle out and the butter can be left to cool and solidify. The butter is
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